Method of making composite metal slabs



Aug. 26, 1941. c. A. 'MEDSKER METHOD OF MAKING COMPOSITE METL SLABSFiled June 22, 1959 '2 Shgeis-Sheet I INVENTOR. CHARLES AJVEDSKER A REZQ M C. A. MEDSKER METHCD OF MAKING COMPOSITE METAL SLABS Aug. 26,1941.

2 Sheets-Sheet 2 Filed June 22, 1939 INVENTOR. CHARLES A.MEusKE/?ATTORNEY.

Patented Aug. 26, 1941 UNITED STATES PATENT OFFICE 7 2,253,526 METHOD orMAKING COMPOSITE METAL SLABS Charles A. Medsker, Cleveland Heights,Ohio, assignor to William L. Ulmer, Cleveland, Ohio Application June 22,1939, Serial No. 280,593 8 Claims. (01. 22-204) This invention relates,as indicated, to a method of making composite metal slabs.

A primary object of the invention is to provide a method wherebycomposite metal slabs characterized by an extremely strong bond betweenthe component metals thereof, may be easily and quickly made in acontinuous or intermittent manner. I

To the accomplishment of the foregoing and related ends, said invention,then, consists of the steps hereinafter fully described and particularlypointed out in -the claims; the annexed drawings and the followingdescription setting forth in detail one mode of carrying out theinvention, such disclosed mode illustrating, however, but one of variousways in which the principleof the invention may be used.

In said annexed drawings Fig. l is a side elevational view of apparatusembodying the invention;

Fig. 2 is a transverse cross-sectional view of the apparatus, taken onthe line 22 of Fig. 1;

Fig. 3 is a plan view of the apparatus;

Fig. 4 is a perspective view, on an enlarged scale, of one of theportable slab molds;

Fig. '5 is a transverse cross-sectional view of the mold, taken on theline 5-5 of Fig. 4';

Fig. 6 is a perspective view of a modified form of slab mold; and

Fig. 7 is a transverse cross-sectional view, taken on the line I-'| ofFig. 6.

Referring more particularly to the drawings, the apparatus is seen tocomprise a supporting framework l'consisting of structural memberssuitably secured together,.and having mounted thereon a pair oftransversely spaced longitudinally extending'rails 2, which serve apurpose to be presently described.

Extending transversely of the framework I, adjacent the ends thereof areshafts 3, carrying sprocket wheels 4, in engagement with which is anendless conveyor chain 5, the chain being disposed intermediate thesides of the framework,

framework and" conveyor chain is a preheating furnace which is supportedat its ends by legs Ill. A combustible gas is adapted to be supplied tothe furnace as by means of burner pipes ll, which, in turn, are suppliedby a manifold con duit l2, each of the pipes ll being provided with ahand-controlled valve l3 for regulating the supply of gas thereto. Aportion of the gas supply from the manifold I 2 is by-passed through aconduit l4 and a fluxing device I5, which may be similar to the devicesdescribed in my copending application Serial No. 261,559, and as aresult of 'which a flux is entrained in the gas. Such flux is desirablya vapor phase flux of. the character described in the co-pendingapplications of Bialosky and Sobel,- Serial Nos. 220,560 and 228,398.

The gas, having a flux entrained therein, upon leaving the fluxingdevice 15 passes through a conduit l6 which terminates in a horizontallydisposed burner ll, overlying and extending transversely of theframework l, at a point spaced from the exit end of. the furnace 9. Theburner I1 is provided with a series of downwardly and forwardly inclinedspaced jets l8 through which the gas having the flux entrained thereinemerges, and at which such gas is burned.

Another portion of the gas supply from the manifold I2 is passeddirectly through a conduit l8, which terminates in a horizontallydisposed burner l9, overlying and extending transversely of theframework I at a point spaced forwardly emerges and at which it isburned.

Disposed at the side of the framework i of' the apparatus, at. a pointopp site the burners I1 and I9, is an electric melting furnace 2| havingtrunnions 22, journalled on pedestals 23, whereby the furnace may betilted to discharge the molten contents thereof through the'spout 24 andinto one of the molds to be.now described. g,

Each mold comprises a shallow rectangular open top box 25, formed of asuitable refractory material, and having a rectangular opening 26 in thecentral portion of the bottom thereof. Each mold has secured thereto apair of spaced shafts 21, each shaft being provided with flanged wheels28, which rest on the rails 2 for facilitating movement of the moldsalong the framework I. Each mold is provided with a pair of upwardlyextending lugs 29 and a pair of downwardly extending lugs 30, whichserve a purpose to be presently described.

The apparatus further includes a. hydraulically operated loadingplatform or station 3|, positioned in front of the furnace 9, and anunloading platform or station 32, having an opening 33 therem,corresponding in size with the mold openings 26, the platform 32 beingsupported by pistons 34, which operate in cylinders 35, the pistonsbeing actuated by means of a fluid admissible into and withdrawable fromthe cylinders through a conduit 36. For the purpose of ejecting theslabs from the molds, a hydraulically operated ram 3'! is provided, thefluid for the operation of which is supplied by means of a. conduit 38.

For the purpose of cooling the composite slabs, 'a conduit 39 isprovided, which overlies the framework at a point intermediate thefurnace 2| and the unloading platform 32, and through which water issprayed onto the slabs.

The operation may now be described as follows:

With the mold 25 positioned on the platform 3|, as shown in Fig. 1, aslab of steel or other metal is placed in the mold, such slab beingdesignated by the reference character S in Fig. 5, the upper surface ofsuch slab having been previously prepared, as by suitable machining andcleaning operations. The platform is then ele vated until the mold is ona level with the upper run of the conveyor chain 5, after which the moldis pushed into the preheating furnace 9, with the wheels 28 thereofresting on the rails 2. The lugs 30 of the mold are engaged by theconveyor chain 5, and in this way the mold is caused to slowly traversethe furnace, the slab S being heated up to a desired temperature. v

The mold with the hot slab S therein, is then moved to a positionopposite the furnace 2|, and, while burning gas, having flux entrainedtherein, is directed against the upper surface of the slab S, thefurnace 2| is tilted so as to cause the contents thereof, or at least aportion of such contents to flow into the mold, and onto the slab S. Themetal, thus'poured onto the slab, may be copper or some other materialdifferent from the metal of the slab S, and, due to the action of thevaporizing flux, such metal becomes firmly bonded to the slab S. Theburning gases, issuing from the burners l1 and I9, are of value inpreserving the metal poured onto the slab S in molten condition for asufficient length of time to permit it to spread evenly over the slab,forrning a layer C (see Fig. 5) of such metal.

The mold with the composite slab therein then proceeds to a point belowthe conduit 39, where the slab is cooled by the water issuing from saidconduit. i

The mold then passes onto the unloading platform 32, and while the moldis thus positioned on the platform, the platform is lowered, while theram 3'! remains stationary. As the mold is thus lowered, the .slabengages the ram. which projects upwardly through the opening 26 in themold, with the result that the slab is ejected from the mold, and isexposed for removal to any desired point for further operations thereon,such as rolling.

The platform descends to the level of the rails 8, and the ram 31 islikewise lowered. The empty mold is then pushed onto the rails 8, wherethe lugs 29 thereof are engaged by the lower rim of otherwise be thecase.

may be continuous or intermittent and in order to increase theproductive, capacity of the apparatus, a plurality of molds areprovided.

The furnace 2| is preferably of a size suitable for melting sufficientmetal to fill a large number of molds, and a neutral or reducingatmosphere is desirably maintained within this furnace.

The process thus includes the steps of preheating the backing metalslab, cladding or coating the preheated slab, and cooling the compositeslab. If desired, the slab S, after being coated on one side with acladding metal, may be inverted in the mold, and the other side clad orcoated with a cladding metal of the same kind, or a different claddingmetal.

Instead of using a mold, such as shown in Figs. 4 and 5, an adjustablemold, such as shown in Figs. 6 and '7, may be employed. Such a moldcomprises a steel or platform having mounted thereon side walls 5| andend walls 52, which are lined with refractory bricks 53. In order tovary the size of the mold, the walls 5| may be adjusted, and for thispurpose each of these walls is provided with a plurality of bolts 54having heads 55 which are movable in T-slots 56 in the platform 50. Thewalls 5| are maintained in adjusted position by means of nuts 51, whichare secured to the bolts 54 and are drawn down into engagement with thewalls. By substituting shorter or longer walls for the walls 5|, the endwalls 52 may also be adjusted to further change the size of the mold,additional T-slots 56, bolts 54 and nuts 51 being provided for thispurpose.

The temperature to which the slab S should be preheated will vary bothwith the nature of the cladding metal and with the alloying affinity ofthe cladding metal with the metal of the slab. While high temperaturesare at all times more desirable from the viewpoint of ease of surfacealloying (and therefore of adhesion), the danger of surface oxidation ofthe slab also increases rapidly with high temperatures. The exactpreheating temperature must therefore be a balance between thesefactors. super-heat the cladding metal, the temperature of preheating ofthe base metal or slab can be correspondingly lowered, since thecladding metal, in such case, will supply the necessary heat to thebonding surface.

Certain metals and alloys tend to become alloyed with iron or steel morereadily than others, and since this surface alloying is the criterion ofbonding, the slab'need not be heated to as high a temperature where suchreadily alloyable cladding metals and alloys are employed as would Anexample of this is the copper-zinc brass series. On the other hand,metals such as the silicon bronzes do not readily form surface alloyswith iron 'or steel, and in such case, it is necessary to have as high atemperature at the bonding surface as can possibly be secured.- This maybe accomplished in two ways, i. e. either the-slab itself may be heatedto a relatively high temperature, with the cladding metal at atemperature only slightly above its melting point, or the slab-can beheated to a relatively low temperature and the cladding metal heated toas high a temperatureas is possible in the electric furnace, the onlylimitations in the heating of the cladding metal in such case, being thecharacter of refractory used in the furnace and the volatilizability ofthe constituents of the cladding metal or alloy.

Where a temperature in excess of 800 F. is required for the preheatingof the slab, it i'sdesir- Where it is possible to able that flux of thecharacter described be applied to the slab in the preheating furnace inwhich event the fluxer I is so placed that the gas will passtherethrough before entering the burner pipes He Moreover, instead ofusing a preheating furnace of the direct-fired type, as illustrated, amuiile type furnace may be employed in which 'a neutral or reducingatmosphere may be maintained, in which event, the flux may be entrainedin the gases used for producing such an atmosphere, suflicient oxygenbeing introduced however to insure conversion of the organic borate inthe flux to boric oxide.

The cladding metal may, under some circum stances, be poured onto theslab within the preheating furnace, which, in such case, is so con:structed as to provide an inlet for the molten metal. Where the claddingmetal is poured onto the slab exteriorly of the preheatingfurnace, asillustrated in the drawings, it is desirable and perhaps essential thatthe slab be fluxed at the point of pouring, irrespective of the factthat it has been fluxed whilein the preheating furnace. For claddingwith metals containing volatile constituents, such as zinc-copperalloys, melting by an electric furnace is impractical; since the zincwill become volatilized and burned out. For cladding, with such metals,it is preferred to substitute for the electric furnace melting devicesof lower temperature nature, such as gas-fired crucible furnaces,.etc.

Otherforms may be employed embodying the features of my inventioninstead of the one herein explained, change being made as regards themeans and the steps herein disclosed, provided ,the elements stated byany of the following claims or the equivalent of such stated elements beemployed, whether produced by my preferred method or by others embodyingsteps equivalent to'those stated in the following claims.

I therefore particularly point out and distinctly claim as myinvention:-

1. A method of making a composite metal slab which consists inpreheating a slab of steel to a desired temperature, pouring a moltenmetal predominant in copper onto said preheated slab of the course ofsuch treatment with flux, pouring a second metal, in molten condition,onto said slab.

3. A method, as in claim 2,-in which the com- .positeslab is cooled withwater to hasten the solidification'of the applied metal.

4. A method of making a composite metal slab which consists inpreheating a slab of steel to a desired temperature by means of acombustible gas containing a vaporized flux and then pouring a moltenmetal predominant in copper onto said which consist inproviding-abacking metal and steel,and directing a combustible gascontaining a vaporized flux onto the surface of said steel slab duringsaid pouring operation.

2 Amethod of making a composite metal slab which consists in preheatinga metal slab, directing a combustible gas containing a vaporized fluxonto'the upper surface of said slab, and-during a metal to be appliedthereto, thoroughly cleaning substantially the entire surface of saidbacking metal of all impurities which would interfere with the creationof a sound bond between the backing and applied metal by directing acombustible gas flame having a vaporized flux entrained therein againstsaid surface, and flowing said metal to be applied onto said backingmetal in such a manner as to cause said applied metal tocover-substantially all of said cleaned surface.

'7. The process of cladding metals which comprises providing a basemetal and a metal to be applied thereto, maintaining said base metal inan unfused state, subjecting substantially the entire surface of saidbase metal to the action of a combustible gas flame having a vaporizedflux entrained therein, and, while said base metal ,is under theinfluence of said flame and flux,

applying said metal to be applied onto said base in such a manner as tocover substantially the entire surface of said base metal.

8. The process of cladding metals which comprises providing a base metaland a metal to be applied thereto, maintaining said base metal in anunfused state, subjecting substantially the entire surface of said basemetal to the action of a combustible gas flame having a vaporized fluxentrained therein, and, while said base metal is under the influence ofsaid flame and flux, flowing said metal to be applied onto said base insuch a manner as to cover substantially the entire surface of said basemetal.

CHARLES A. MEDSKER.

